By default, on Windows, Smedge version 2.3.1 or later creates a user account for the Engine to use to perform its work. It does this to ensure that it has permission to perform certain operations that require extra permission, like remapping the network drives.
If you were not using any kind of user account management, you were probably automatically logging in as the default "Administrator" user. When you installed Smedge, it created a named user account. Because the default "Administrator" account does not have a name, per se, only the "Smedge" user account shows up on the log in screen, and it looks like Smedge has destroyed your ability to use your computer.
The good news is that it has not. You can still log in as the original "Administrator" account. Press Control + Alt + Delete at the login screen, and you will be presented with the old login dialog which allows you to type the name "Administrator" manually. Once you are logged in, you should be able to see your old desktop and have everything just like it was.
Once you are logged in, you can use the Control Panel to set the machine to automatically log in as the "Administrator" account again. You do not need to use the "Smedge" account yourself in any way.
Note: Future versions of Smedge will try to make the new user account "invisible" to the login screen, which should elimintate this issue. In those cases, the user account will still be created, but you will have to use the Control + Alt + Delete trick (or another manual way to specify the user name) if you want to log in as the Smedge user account.
Remember also that if you specify an account for the Engine to use in the installer, Smedge will simply try to use that account, and will not create the "Smedge" user account on the system at all.